I think polytrip's main point (and one i was going to make before he beat me to the punch

), may have gotten lost in the shuffle.
The study is specific to the UK. The UK has a much mediatized evolving culture of binge drinking, and alcohol has historically been their drug of abuse of choice. It is not surprising at all that a harmful drug that is widely used and accepted does more harm to the society in question than a harmful drug that is marginalized and exponentially less common.
A study in Algeria likely would have found that hashish is the most harmful to algerian society, as one in afghanistan surely would have placed opium and heroin well above alcohol. Sheer numbers...
One must be careful in interpreting studies like these (and in believing the interpretations of journalists, who are certainly not without agendas of their own). It is important in this particular study not to disregard its geographic and cultural specificity, which, far from being a flaw in the study, is its very point. The UK needs to sober up!!8)
Damn, after that i think i need a cupla finngores o dee ole sin-gull mauled!!
Cheers and bottoms up,
JBArk
EDIT: a very useful exercise would be to measure the use in the population of each drug and juxtapose the results with the results of the above study. It would then be surprising to some to see that a drug used/abused by 75% of the population (alcohol) is followed so
closely in its "harm to society" index as one used by only 10% of the population. And yes, for the sake of the argument, i invented the numbers, but i betcha they'd actually prove to be very conservative!